Routes and Mechanisms of SNARE Recycling within the Endomembrane System

Abstract

The endomembrane system describes the series of organelles and membrane-bound structures within which proteins are synthesized, packaged, and transported to various locations within the cell or are secreted from the plasma membrane. In order to facilitate these activities, trafficking machinery must be involved at the site of vesicle biogenesis at the donor membrane as well as the site of fusion at the target membrane. To achieve this last step, SNARE proteins within both the vesicle and target membranes form tight trans-SNARE complexes, conferring specificity and driving fusion. If additional rounds of transport are to occur, this trafficking machinery must be returned to its original compartment where it can complete its function. Budding yeast, and other eukaryotes, have developed sophisticated mechanisms of recycling SNARE proteins that rely on multiple routes of retrieval and post-translational modifications, like ubiquitination, in order to support efficient recognition and recycling of these components.